Sectional upward acting doors are ubiquitous in applications for cargo bodies of freight vehicles, including motor trucks, for example. Mobile cargo bodies are, of necessity, fabricated of components which are as light in weight as practical in order to reduce the tare weight of the vehicle. Sectional upward acting doors for cargo bodies are preferably manufactured of lightweight extruded materials including aluminum and plastics. However, one problem associated with the design and manufacture of sectional doors pertains to the stiffness of the door panels required to resist damaging deflections due to rough treatment, windloads and impacts from shifting cargo. Accordingly, efforts to fabricate sectional doors to be as light in weight as possible are at cross purposes with efforts to make the doors structurally stiff and rugged.
Upward acting sectional doors of the type described above are typically fabricated with multiple panels that are interconnected by spaced apart hinge assemblies. Such hinge assemblies are typically formed by opposed hinge plates which are, preferably, provided with hinge bearing pins interconnecting the opposed plates to form the hinge connection between door panels or sections. In accordance with the present invention, the problem arising from the lack of stiffness of sectional door panels for mobile cargo bodies has been overcome by utilizing the hinge connections between adjacent panels in an improved manner.